The broad, long-term objective of this work is to improve the quality of health care by creating consumer health IT that is aligned with the needs and preferences of diverse patient subpopulations. Many forms of consumer health IT are being developed to support patients in the tasks of health management as health care moves from institutional to home- and community-based settings. However, the design of health IT is rarely grounded in an in-depth assessment of users' needs and preferences, resulting in solutions that are not responsive to the ways in which patients approach health management. The objective of this study, therefore, is to develop patient-centered design guidance for consumer health IT that supports one health management task: health information communication with members of patients' social networks (e.g., family members, friends, online acquaintances) based on an understanding of patients' existing use of a popular online social networking site, Facebook, for health communication. This objective will be accomplished through two specific aims: 1) to generate general design guidance for consumer health IT based on an explication of the ways in which Type 2 diabetes patients engaged with Facebook leverage this technology to support health information communication with members of the social network and 2) to generate design guidance for unique segments of the user population based on an understanding of how Type 2 diabetes patients engaged with Facebook cluster into different patterns or styles of health information communication with members of the social network. This mixed methods study will be grounded in macroergonomic theory and will consist of three phases. In Phase One, qualitative methods will be used to gain a rich understanding of the ways in which patients use Facebook for health information communication with members of the social network. In Phase Two, the findings from this qualitative exploration will be used to create and pilot a structured questionnaire. In Phase Three, a large- scale survey of Type 2 diabetes patients engaged with Facebook will be used to assess the overall prevalence of specific health information communication practices through descriptive statistics and to define particular segments of the patient population based upon these practices through cluster analysis. The qualitative and quantitative components of the study will be synthesized and translated into general and segment-specific design guidance for consumer health IT. Throughout all study phases, the purposeful sampling strategies employed will help ensure that the study population is inclusive of both genders and the five racial and two ethnic groups of primary interest to AHRQ. Thus, the proposed study will accelerate the development of health IT that effectively supports patient-centered care across diverse patient subgroups. This work will serve as a foundation for our future research efforts, which will 1) assess the feasibility and value of integrating this form of design guidance into the design process and 2) assess the impact of consumer health IT grounded in this design guidance on outcomes such as use, usefulness, usability, satisfaction, and, ultimately, health outcomes.